On May 22^{th}
2015 Jose Mourinho was chosen as the Premier
League Manager of the Season. Jose Mourinho have been the coach in the
Chelsea and Chelsea has won the English Premier League. For sure it is a huge accomplishment,
but, maybe it is not enough to be named with this award. It is well known that this kind of prizes used to
reward the head coach of one of the strongest teams as it can be seen in either
in the list of NBA coach of the year or in the list of World Soccer coach of the year. However, this kind of prizes should not be to one of
the head coach of the best teams but to coach that has obtained the most given
its rooster. An alternative to evaluate objectively the managers’
performance is to compare the actual results with those expected from betting odds.
The probability of the three possible outcomes in a game (i.e., local victory,
draw and away victory) is embedded in betting odds so that it is enabled to
calculate the probability of getting each of the possible number of victories.
Odds for
football matches offered in the betting market can be reconverted into
probabilities for each possible result (home win, draw, away win). If the
betting market were efficient, these probabilities would reflect the true
probabilities of each event. Although there is no consensus in the literature
whether or not betting odds are efficient, it seems that any inefficiency that arises
is very small. Thus, the probabilities embedded in betting odds can be seen as
true probabilities. The European domestic football leagues are generally
organized in a double round robin basis, where each team plays against the
other teams once at home and once away. Winning teams are awarded three points,
a draw earns one point for each team, and the losing team earns no points. The
final league ranking is made on the basis of points earned at the end of the
double round robin.
Basic
probability theory tells us that the joint probability of two independent
events (e.g., a victory of the same team in two different football matches) equals the product of their probabilities.
Using this simple formula for all possible combinations of match results of
each team, the probability of each team within a league obtaining a certain
amount of points can be computed, that is, the density function of total points
at the end of the season. The total points ranges between zero (i.e., the team
loses all matches) and the product of the number of matches and three (i.e.,
the team wins all matches).
In particular,
we use the betting odds from www.betexplorer.com,
which provides the average of the betting odds from several bookmakers, in
order to calculate the density functions for the 201415 season for English
Premier League. The cumulative density function can be used to calculate the
probability of getting more points than the actual result. The inverse of that
probability can be viewed as an efficiency index for managers in the sense than
the closer the value to one will reflect a better performance and the closer
the value to zero will reflect a worse performance. The managers with higher
efficiencies would be the teams that have overperformed the results expected
from the odds. The overperforming could be due to luck or fortunate referees’
decisions, but the most plausible reason to overperform the expected results
from the odds is good coaching, in the same way the underperformance of the
teams could be due to injuries or bad luck but the most plausible is bad
coaching. Thus, the efficiency index can be understood as a measure of the
performance of the managers.
Table 1 shows
the managers’ efficiency for each team in the season 2014/2015. It can be seen
that the team most efficient was the Swansea, that obtained 56 points which is
certainly a huge amount for the Swansea. It is followed by José Mourinho, but
the second one in this list should not be named as the Premier League Manager
of the season.
Table 1.
Efficiencies of the managers/teams in the season 2014/2015
Manager

Team

Efficiency

Points

Garry Monk

Swansea

0.91

56

José Mourinho

Chelsea

0.85

84

Mark Hughes

Stoke City

0.82

51

Keith Millen and others

Crystal Palace

0.76

45

Mauricio Pochettino

Tottenham

0.74

61

Sam Allardyce

West Ham

0.69

47

Arsène Wenger

Arsenal

0.68

72

Alan Irvine and othrs

West Brom

0.60

44

Ronald Koeman

Southampton

0.59

60

Paul Lambert and others

Aston Villa

0.55

38

Manuel Pellegrini

Manchester City

0.54

76

Louis van Gaal

Manchester United

0.54

69

Gustavo Poyet and others

Sunderland

0.50

38

Brendan Rodgers

Liverpool

0.37

62

Nigel Pearson

Leicester

0.33

38

Harry Redknapp and others

QPR

0.25

30

Steve Bruce

Hull City

0.24

34

Sean Dyche

Burnley

0.22

30

Roberto Martínez

Everton

0.21

47

Alan Pardew and others

Newcastle Utd.

0.18

36

Notes: elaborated using the betting odds
from www.betexplorer.com
Teams are ordered by the efficiency
level.
Hence, it was
not fair the election of Mourinho as the Premier League Manager of the Season,
instead Garry Monk should have been awarded.
Lastly, it is
important to note that these calculations have been carried out taking into
account only the English Premier League.
Julio del Corral
Cuervo is Associate professor in Economics at the University of CastillaLa
Mancha (Spain)
No hay comentarios:
Publicar un comentario